Railway traffic controlling apparatus



Feb. 9, 1937. THOMPSON 2,069,905

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Sept. 26, 1955 3 Sheets-Sheet 1 INVENTO'R Howard A. Thompson.

BYQR' I HIS ATTORNEY Feb. 9, 1937. THOMPSON 1 2,069,905

RA ILWAY TRAFF I C C ON TROLLI NG APPARATUS Filed Sept. 26 1935 3 Sheets-Sheet INVENTOR Howard/1. Thom 012.

m5 ATTORNEY Feb. 9, 1937. THOMPSON 2,069,905

RAILWAY TRAFFI C C ONTROILILING APPARATUS Filed Sept; 26, 1935 I 5 Sheets-Sheet 3 INVENTOR Howard A. fyzonyvson HIS ATTORNEY Fig.5.

Patented Feb. 9, 1937 UNlTED ST TS RAILWAY TRAFFIC CONTROLLING APPARATUS Howard A. Thompson,

Edgewood, Pa, assignor Appiication September 26, 1935, Serial No. 42,215

15 Claims.

My invention relates to railway traffic controlling apparatus, and particularly to apparatus for control circuits for railway signaling systems. The present application is a continuation in part of my copending application filed May 3, 1935, Serial No. 19,684, for Railway trafiic controlling apparatus, which latter case is a division of my copending application filed July 13, 1932, Serial No. 622,257, for Railway traflic controlling apparatus, now United States Patent No. 2,018,818, issued October 29, 1935.

I will describe three forms of apparatus embodying my invention. and will then point out the novel features thereof in claims.

A feature of my invention is the provision of a double wire control circuit using one relay for each wire, so arranged that an accidental connection of a control wire with the current source is detected either immediately or at the next operation of the apparatus. A further feature of my invention is the provision of a novel and improved arrangement for control relays for signal systems whereby false operation of a relay results in a more restricted signal indication, and whereby signal flashing and circuit tumble-down conditions are avoided. Other features and advantages of my invention will appear as the specification progresses.

In the accompanying drawings, Fig. l is a diagrammatic view of a preferred arrangement of apparatus and circuits embodying my invention for a standard three-indication wayside signaling system. Figs. 2 and 3 are diagrammatic views of apparatus and circuits for a four-indication wayside signaling system and each of which embodies my invention.

In each of the several views like reference characters designate similar parts.

Referring to Fig. 1, the trafiic rails 5 and 5 of a stretch of railway are divided into successive track blocks by the usual insulated rail joints. In Fig. 1 only one full block A-B is disclosed, together with the adjoining ends of two adjacent blocks. This track block AB is divided into two sub-sections AAl and AlB each of which is provided with a track circuit including the usual track relay, here designated by the reference character TR plus an exponent correspending to the location, and the usual source of current such as a battery TB. The wayside signals SA and SB govern traffic in the direction indicated by the arrow. These signals may be of the semaphore, or color light, or position light type and are here shown as threeposition color light signals capable of displaying clear, approach and stop indications by the illumination of a green lamp G, a yellow lamp Y and a red lamp R, respectively. The operating circuits for each wayside signal are governed by two control relays here designated by the reference characters HR and DR with exponents added to designate the location. These operating circuits are alike for all signals, .and it is thought a description of those for one signal will serve for an understanding of all. Referring to signal SA, for example, this signal is provided with a clear operating circuit that passes from the positive terminal of a battery 26, through front contact 21 of the relay DRA, back contact 28 of relay HRA, wire 29, G signal lamp 84 and the common return wire 4 to the negative terminal of battery 26. The approach operating circuit is from battery 25, through back contact 38 of relay DRA, wire 3!, front contact 32 of relay HRA, wire 33. Y signal lamp and common return wire i to battery 26. The stop operating circuit includes battery 25, back contact 30 of relay DRA, wire 3 l back contact 34 of relay HRA, wire 35, R signal lamp B6, and common return Wire i. It follows that with control relay HRA deenergized and control relay DRA energized the clear operating circuit is closed, with relay I-IRA energized and relay DRA deenergized the approach operating circuit is closed, and with both of these relays deenergized the stop operating circuit is closed. In other words the signal SA is set to display a proceed indication (clear or approach) only when the respective control relay is energized and the other control relay is deenergized.

These two control relays ERA and DRA are controlled by a double wire control circuit which is governed by traffic conditions in advance in the following manner. Normally current is supplied from a battery 36 at the signal location SB in advance, over wire 31, back contact 38 of relay HRB, front contact 39 of relay DRB, control wire 2 front contact l!) of track relay TRAl, control wire 2, front contact 4! of track relay TRA, winding of relay DRA and the common return wire 4 to the opposite terminal of battery 36. Also, if the relay HRB at signal location SB is energized and relay DRB is deenergize-d, the control relay DRA supplied with current from the battery 36, the circuit including wire 31, front contact 42 of relay I-IRB, back contact 43 of the relay DRE, control wire 2 and thence as before traced. It follows that relay DRA is energized over the contrcl wire 2 when either one of the control relays HRB or DRB at the signal location SB in advance is picked up and the other control relay down; In the event both control relays at the signal location SB are deenergized the relay HRA is supplied with current from battery 36 over wire 31, back contact 38 of relay HRB, back contact 44 of relay DRB, control wire 3 front contact 45 of track relay TRAI, control wire 3, front contact 46 of track relay TRA and winding of relay HRA to the opposite terminal of battery 36 over the common return Wire 4.

As both control wires 2 -2 and 3 3 are carried through front contacts of track relays TRAI and TRA, it is clear that both the control relays HRA and DRA are deenergized when either of the track sections of block AB is occupied, and the signal SA then indicates stop. At the signal location SB both the control wires 2 and 3 associated with the relays DRB and HRB are carried through front contacts of the track relay IRB, and thus both of these control relays are deenergized when the block to the right of signal location SB is occupied. As described hereinbefore, with both relays HRB and DRB down, the control relayI-IRA is supplied with current over its control. wire 3 3 and that relay is then energized. It follows, that with the first block in advance of signal SA unoccupied and the second block in advance occupied relay HRA is up and relay DRA is down, and the signal SA indicates approach. The control of the relays DRB and BBB is similar to the control of relays DRA and HRA and this being so it is clear that when one block in advance of the signal SB is unoccopied and the second block in advance is co- 'cupied, relay HRB is up and relay DRB is down. Thus, if block A--B is also unoccupied, the relay DRA is energized and relay HRA is deenergized causing the signal SA to display a clear indication. Furthermore, when two blocks in advance of signal SB are unoccupied, and relay DRB is up andrelay HRBis down, the relay DRA at signal SA is also supplied with current by the circuit heretofore traced and which circuit includes the back contact 38 of relay HRB as well as the front contact 39 of relay DRB, and the signal SA' displays a clear indication.

A negative cross on control wire 2-2 will be at once detected by the shunting of the control relay DRA and the setting of the signal SA at stop. A positive cross on control wire 33 will be at once detected by the picking up of relay HRA and signal SA being made dark. A positive cross on control wire 2--2 will be detected the next time the block in advance of signal SB becomes occupied, by the energizing of relay DRA and, as relay I-IRA is now picked up, the signal SA will be made dark. A negative cross on control wire 33 will bedetected the next time the block in advance of signal SB is occupied, by the shunting of relay ERA and the consequent setting of signal SA at stop. Hence, in Fig. l, a double wire control circuit is pro vided for governing the signal controlling relays and the principleof requiring one control relay to be energized and the other control relay to be deenergized before an operating circuit for displaying a proceed indication is closed is emplcyed. In the case of track relay TRAI the control wires 2 and 3 are shunted by back contacts 81 and 88 when the relay is down. This is to prevent a positive cross on either control wire 2 or 3 of section A-.-A| causing a false energization of a control relay when relay TRAI is deenergized;

The control relays HR, and DR at each location of Fig. 1 are provided with slow release characteristics, and signal flashing and a tumbledown of control circuits to the rear during the interval the relays of a location are changing positions in response to a change in traflic conditions are avoided. For example, if the block to the right of location B is occupied by a train and the block A-B is unoccupied, the relay HRA is picked up and the relay DRA is down and the Y lamp of signal SA is'illuminated. Assuming the train in the block to the right of location B now advances and vacates that block and the relay HRB is picked up, the control circuit for' relay HRA is opened at the back contact 38 of relay BBB and the control circuit for the relay DRA is closed at the front contact 42 of relay BBB, and relay HRA is deenergized and the relay DRA is energized. During this change in the positions of relays HRA and DRA, the Y lamp circuit for signal SA is opened at the back contact ing circuit for the R lamp of signal SA momentarily closed and a stop signal flash is avoided. Furthermore, prior to and immediately following such change in the positions of relays ERA and DRA the same line control wire 2 leading to the rear from the location A is connected with the positive terminal of the battery 26 and hence an interval occurs during which such line circuit is without energy. Since the relays at the location to the left of location A are also slow releasing in character, the interval during which no current is supplied to the line circuit leading to the rear of location A does not effect a release of a control relay at such location in the rear. In other words, a tumble-down condition of the relays at the successive signal locations to the rear of location A due to a change in the position of the control relays at location A is avoided.

A false operation of a control relay results in a more restrictive indication being displayed. Looking at location A of Fig. 1, if the relay DRA, for example, should fail to pick up when its control circuit is closed to effect a clear indication, the operating circuit for the R lamp is closed and signal SA displays a stop indication, since the other control relay HRA is deenergized at such time as the control circuit for relay DRA is completed. Likewise, should the relay HRA fail to pick up in response to the closing of its control circuit to effect an approach indication, the signal SA displays a stop indication since at such time the relay DRA is without energy and the operating circuit for the R lamp of signal SA is closed. Again, should either relay I-IRA or DRA fail to release in response to its control circuit being opened and the other control circuit being closed, the signal SA is left dark since under such circumstances both control relays DRA and HRA are picked up and no operating circuit for the signal SA is closed.

When applying the principle of a double wire control circuit with a relay for each wire, one of which must be energized and the other gized, to a four-indication wayside signal system, three control relays are provided. Refer ring to Fig. 2, the control relay GR is added to the control relays HR and DR of Fig. 1, and these three relays are so arranged that when any one of them is energized, the other two must be deenergized in order to close an operating circuit effective to cause a proceed indication to be displayed by the associated signal. In Fig. 2 only one signal location is illustrated, but it will be understood that the stretch of railway to be protected is provided with successive signal locations similar to that shown in Fig. 2. In accordance with standard practice for four-indication signaling, the color light signal S is provided with two groups of lamps, the top group Gl consisting of three lai'nps G, Y and R adapted to display a green, a yellow and a red signal light, respectively. The bottom group of lamps G2 consists of two lamps G and R capable of displaying a green and a red signal light, respectively. When the immediate block in advance of signal S is occupied, the R lamp of each group is lighted and the signal indicates stop. When the first block in advance is unoccupied and the second block is occupied, the Y lamp of the top group and the R lamp of the bottom group are lighted, and the signal then displays a yellow light over a red light to give the approach indication. When two blocks in advance are unoccupied and the third block occupied, the Y lamp of the top group and the G lamp of the bottom group are lighted, and the signal then displays a yellow light over a green light to give the approach-restrictive indication. When three or more blocks in advance are unoccupied, the G lamp of the top group and the R lamp of the bottom group are lighted, and the signal then displays a green light over a red light to give the clear indication.

When the block in advance of signal S is occupied and track relay TR shunted, all three control relays HR, DR and GR are deenergized as will be evident from an inspection of Fig. 2. A circuit is now closed for the R lamp of the top group GI from battery terminal B through back contacts 53, 9| and 92 of relays HR, DR and GR, respectively, and thence to the negative terminal C through the lamp R of the top group. A circuit for the R lamp of the bottom group G2 extends from the terminal 13 through back contacts 93 and 94 of relays HR and DR, respectively, and thence through the R lamp of the bottom group to the negative terminal C. Thus with the block immediately in advance of signal S occupied, the signal displays a red light above a red light to indicate stop. Under this traffic condition the battery terminal B is connected to the control wire l leading to the signal location in the rear of signal S. This circuit includes the back contacts 95, 96 and 91 of relays GR, DR and HR, respectively, and this circuit is effective to energize the HR relay at the location in the rear, the wire l being connected with the HR. relay in the rear in the same manner as control wire I is connected to the HR relay of signal S.

In the event the second block in advance of signal S is occupied and the immediate block in advance unoccupied, the control wire I from the signal location next in advance is supplied with current in the same manner as just described for the control wire I and thus the relay HR at signal S would be energized. With relay HR picked up and both relays DR and GR down, the Y lamp of the top group Gl is energized over the front contact 98 of relay HR and back contacts 99 and W of relays DR and GR, respectively.

At the same time the R lamp of the bottom group G2 is energized over the front contact IDI of relay HR and back contacts :02 and H13 of relays DR and GR, respectively. Thus with the immediate block in advance of signal S unoccupied and the second block in advance occupied the signal displays a yellow light above a red light to effect the approach indication. Under this trafiic condition the control wire 2 leading to the signal in the rear is supplied with current over the back contacts 95 and 96 of relays GR and DR, respectively, and the front contact Hit of relay HR, to energize the DR relay at that signal, the wire 2 being connected to the DR relay in the rear in the same manner as wire 25 is connected to relay DR at signal S.

With two blocks in advance of signal S unoccupied and the third block occupied, the control wire 2 is connected to the positive battery terminal at the signal next in advance in a manner similar to that just described for the control wire 2, and thus the control relay DR at signal S is now picked up and relays HR and GR both down. Under this set-up of the control relays the Y lamp of the top group GI is energized over back contact 53 of relay HR, front contact I of relay DR and back contact I00 of relay GR; and the G lamp of the bottom group G2 is energized over back contact 93 of relay HR, front contact Hit of relay DR and back contact ID! of relay GR. Thus under this trafiic condition the signal S displays a yellow light above a green light to effect the approach-restrictive indication. The control wire 3 is now connected to the battery terminal B through back contact Q5 of relay GR, front contact H38 of relay DR and back contact 189 of relay HR, and the control relay GR at the signal location in the rear is energized, the control wire 3 being connected with the GR relay at the location in the rear in the same manner the wire 3 is connected to the GR relay at signal S. With three blocks in advance of signal S unoccupied and the fourth block occupied, the control wire 3 will be supplied with current at the signal location in advance in the same manner as just pointed out for the control wire 3 and hence relay GB at signal S will then be picked up and both relays HR and DR will be down. Under this condition of the control relays, the G lamp of the top group GI is energized over the back contacts 53 and 9| of relays HR and DR, respectively, and the front contact H0 of relay GR; while the R lamp of the bottom group G2 is energized over back contacts 93 and 94 of relays HR and DR, respectively. Hence with at least three blocks in advance of signal S unoccupied the signal displays a green light above a red light to efiect the clear indication.

With the apparatus in the position illustrated in Fig. 2 and a positive cross occurs in the line wire 2 and relay DR is picked up, current is removed from the G lamp of the top group at the back contact 9| of relay DR and from the R lamp of the bottom group G2 at the back contact 94 of that relay, and the signal S is dark. This false energization of the relay DR removes current from the line wire 3 leading to the rear and the signal in the rear of signal S is set to display a stop indication since its control relays are now all deenergized. Again with a positive cross on the line wire I and the relay HR is energized, current is removed from the illuminated G and R lamps of signal S at the back contacts 53 and 93 of relay HR with the result the signal S is now dark. Current would also be removed from the line wire 3 leading to the rear and the signal in the rear would be set at stop due to its control relays being now all deenergized. A negative cross of the line wire 3 would shunt the relay GR and signal S would display a stop indication since all three of its control relays would now be down. An analysis of the effects of crosses or grounds on the line wires in other positions of the signal S will disclose a similar effect which causes the signal S to be dark and the signal in the rear to be set at stop,if a positive cross appear on either of the two line wires not at the time connected with the current source.

It is clear from Fig. 2 that line control circuits 1 provided with a relay for each circuit and arranged for one relay to be energized and the remaining relays to be deenergized for closing an operating circuit effective to establish a proceed indication (clear, approach, or approach-restrictive) are adaptable to a four-indication wayside signal S, and when so applied a false proceed indication due to a cross on a line wire is avoided. That is, an accidental connection of a line wire with the current source results in the signal displaying a more restrictive indication than it would otherwise display.

Substantially the'same check against crosses and grounds obtained in Fig. 2, may be obtained for the control circuits for a four-indication wayside signal system by making each proceed indication the result of two relays energized and a third relay deenergized. Such modification of the circuits and apparatus embodying my invention is disclosed in Fig. 3. Referring to Fig. 3,

' only one signal locationis illustrated the same as in Fig. 2 and it will be understood that the stretch of railway to be protected is arranged in successive track blocks each of which is provided with signal equipment similar to that illustrated in Fig. 3. The signal S of Fig. 3 comprises two groups of lamps GI and G2 which are displayed in the manner explained for the signal of Fig. 2

and it is thought to be unnecessary torepeat the description.

Three control relays HR, DR and GR are provided in Fig. 3 each of which has one terminal of its operating winding connected with the common return wire as indicated at C and the other terminal connected with an associated line wire over a front contact of the track relay TR the same as in Fig. 2. It follows that with the block immediately in advance of signal S occupied and the track relay TR released, all three control relays HR, DR and GR are deenergized. Under this set up of the control relays the R lamp of the top group G2 receives current from the B battery terminal over back contacts H3, H4 and H5 of relays HR, DR and GR, respectively, and is illuminated. The R lamp of the bottom group G2 receives current from the B battery terminal over back contacts H6, H1 and H8 of relays HR, DR and GR, respectively, and is illuminated. Signal S thus displays a red light above a red light to indicate stop when the block immediately in advance of the signal is occupied. Under this traffic condition where all three of the control relays are deenergized, the line wires I f and 2 leading to the rear of signal S are both connected with the current source, the connection for line wire I including the B battery terminal, back contacts H9, I and I2I of the relays GR, DR and HR, respectively; and the connection for the line wire 2 including the B battery terminal, back contacts IIS, I22 and I23 of relays GR, DR and HR, respectively. The line wires I and contact 2 are each connected with the HR and DR relays at the location in the rear in the same manner as the corresponding line wires I and 2 are connected with the relays HR and DR at the location illustrated in Fig. 3, and thus these two' cation in advance in the same manner just explained' for connecting the line wires I and 2 to the current source and hence relays HR and DR are energized and the relay GR is deenergized in response to this trailic condition just cited. Under this set up of the control relays the Y lamp of the top group GI receives current from the B battery terminal over front contacts I24 and I25 of relays HR and DR, respectively, and back contact I26 of relay GR, and is iluminated. The R lamp of group G2 now receives current from B battery terminal over front contacts I21 and I28 of relays HR and DR, respectively, and back contact II8 of relay GR, and is iluminated. Hence, when the first block in advance is unoccupied and the second block is occupied, the signal S displays a yellow light above a red light to indicate approach.

The line wires I and 3 leading to the rear of signal S are now connected with the B battery terminal, the connection for wire I includ- 7 ing back contact II9 of relay GR and front contacts I29 and I30 of relays DR and HR, respectively; and the connection for wire 3 including back contact H9 of relay GR and front contacts I3I and I32 of relays DR and HR, respectively. Thus the HR and GR control relays at the location in the rear are now energized since the line wires I and 3 are connected with these relays in the same manner as the line wires I and 3 are connected with the relays HR and GR at the location of signal S.

Since the line wires I and 3 are each connected with the current source at the location in advance of signal S in the same manner as just explainedfor line wires I and 3 leading to the rear, it follows that when two blocks in advance of signal S are unoccupied and the third block in advance is occupied, the 'two control relays HR and GR at signal S are energized GR, and is illuminated. The G lamp of the bottom group G2 receives current from the 3 battery terminal overfront contact I2'I'of relay HR, back contact I35 of relay DR and front I36 of relay GR, and is illuminated; Consequently, when two blocks in advance of signal S are unoccupied and the third block in advance is occupied, signal S displays a yellow light above a green light to indicate approachrestrictive. This time the 2 and 3 line wires leading to the rear are supplied withcurrent, the connection for line wire 2 including front contact I31 of relay GR, back contact I38 of relay DR and front contact I39 of relay HR; and the connection for line wire 3 including front contact I31 of relay GR, back contact I40 of relay DR and front contact I32 of relay HR.

Thus the DR and GR control relays at the location in the rear are energized in response to this traffic condition just cited.

The line wires 2 and 3 are connected with a current source in the location in advance in the same manner as just explained for the line wires 2 and 3 It follows that when three blocks in advance of signal S are unoccupied and the fourth block is occupied, the DR and GR relays at signal S are picked up and the HR relay is released. Under this set up of the control relays, the G lamp of group G! receives current from the B battery terminal over back contact N3 of relay HR, and front contacts MI and I42 of relays DR and GR, respectively, and is illuminated. The R lamp of group G2 now receives current over back contact N6 of relay HR and the front contacts M3 and M4 of relays DR and GR, respectively, and is illuminated. Hence, signal S displays a green light over a red light to indicate clear when three blocks in advance of the signal are unoccupied and the fourth block is occupied. The line wires 2 and 3 remain connected with the current source under this condition of the control relays, the connection for the line wire 2 now including front contacts 13'! and M! of relays GR and DR, respectively, and back contact I23 of relay HR; and the connection for the line wire 3 including front contacts 131 and M5 of relays GR and DR, respectively, and back contact I46 of relay HR. Thus this change in the traflic conditions in advance of signal S from two blocks unoccupied and the third block occupied to three blocks unoccupied results in no change in the energization of the control relays at the location in the rear of signal S. It is clear, therefore, that when four blocks in advance of signal S are unoccupied the DR and GR relays at signal S remain energized and the HR relay deenergized and signal S continues to display a clear indication.

With the apparatus of Fig. 3 in the position illustrated and a positive cross occurs on the line wire l and the control relay HR is picked up, the signal S is made dark since the operating circuits for the illuminated lamps G and R are opened at the back contacts H3 and H6 of relay HR. With all three control relays HR, DR and GR picked up at the same time each of the line wires I 2 and 3 is disconnected from the current source and hence all three control relays at the signal location in the rear are deenergized and the signal at that location is set to display the stop indication. With the apparatus of Fig. 3 set to cause the signal S to display either the approach or the approach-restrictive indication and a positive cross occurs on the line wire not at the time connected with the current source so that the three control relays are energized, the signal S is made dark and the signal in the rear is set at stop in the same manner explained above. That is, in case two relays are energized to give a proceed indication (clear, approach, or approach-restrictive) if the third relay is falsely energized, a dark signal is produced and the signal to the rear is set at stop. In case all three relays are deenergized and the stop indication is displayed, the false energization of any one relay alone would not give a proceed indication, but the signal would be made dark and the signal to the rear would be set at stop.

Although in Figs. 2 and 3, a wayside signal consisting of two groups of, lamps, the top group including three lamps and the bottom group including two lamps is disclosed, it will be understood that my invention is not limited to this one form of signal and other arrangements of lamps may be used if found desirable to do so. As a matter of fact, in practicing my invention, the bottom group of lamps may be made a single lamp which is illuminated only for one specific indication.

It is tobe noted that the control relays of Figs. 2 and 3 are made slightly slow releasing and thus upon a change from one proceed indication to another proceed indication there is no interval when all three control relays are down with the result flashing of the red lamps is avoided. Furthermore, a tumble-down condition of the relays at the successive signal locations to the rear of signal S due to a change in the position of the control relays at signal S is avoided in the manner similar to that explained for Fig. 1, since no current is supplied to any of the line wires leading to the rear during the interval the relays of signal S are changing positions and the slow release characteristic of the relays at the location in the rear bridges this gap.

A false operation of a control relay, in the forms of the invention disclosed in Figs. 2 and 3, will result in a more restrictive indication being displayed. Looking at Fig. 2, if a relay fails to pick up in response to its associated traffic condition all three relays would be left deenergized and signal S would be set at stop. If a relay fails to release under traffic conditions during which it is deenergized, the signal S would be dark and the signal to the rear would be set at stop, since with two relays up at one time all circuits are opened. In Fig. 3, if one relay fails to pick up, the condition of the control relays would be one relay up and two down, and under such setup of the relays the signal S would be dark and the signal to the rear would be set at stop. Again if a relay fails to release, in Fig. 3, the set-up would be all three relays picked up and signal S would be dark and the signal to the rear would be at stop.

It is clear from Figs. 2 and 3 that a double wire control circuit, and the principle of checking the position of. each control relay for completing an operating circuit, are adaptable to the control circuits for a signal system providing four or more distinctive indications, and when so applied exactly the same protection against the possibility of a false clear operation by a positive or negative cross on a control wire as heretofore described is provided.

Although I have herein shown and described only three forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track, a signal having a first and a second position for governing trafiic through said stretch, line circuit means including two control wires and a common return wire, a source of. current having one terminal permanently connected to the common return wire, a relay associated with each control wire and having its winding connected between its control wire and the common wire, traflic controlled means adapted to connect one control wire to the other terminal of the current source under one traffic condition and to connect the other control wire to said otherterminal under other traific conditions whereby one of said relays is energized under the first mentioned trafiic condition and the other relay is energized under said other trafiic conditions, a first operating circuit for operating said signal to its first position and including a front contact of the first mentioned relay and a back contact of the second relay in series, and a second operating circuit for operating the signal to its second position and including a back contact of the first mentioned relay and a front contact of the second relay in series.

2. In combination, a stretch of. railway, a signal having a plurality of distinctive positions to display a plurality of distinctive indications for governing trafiic through the stretch, a line circuit for each position of said signal and governed by traflic conditions in advance, a line relay for each position of said signal controlled by the corresponding line circuit, and an operating circuit for each position of said signal for causing the signal to display the corresponding indication and each of which circuits includes a front contact of the line relay controlled by the corresponding line circuit and a back contact of each of the remaining relays in series. r

3. In combination, a stretch of railway, a wayside signal having at least three distinctive positions to display three distinctive indications for governing trafiic through the stretch, a control relay for each position of said signal and responsive to traffic conditions inadvance, and an operating circuit for each position of said signal for causing the signal to display the corresponding indication and each of which circuits includes a front contact of the control relay corresponding to the same position of said signaland a back contact of, each of the remaining control relays in series.

'4. In combination, a stretch of railway, a wayside signal having at least three distinctive positions to display three distinctive indications for governing traffic through the stretch, a control relay for each position of said signal and responsive to traflic conditions in advance, an operating circuit foreach position'of said signal for causing the signal to display the corresponding indication and each of which circuits includes a front contact of the control relay corresponding to the same position of said signal and a back contact of each of the remaining control relays in series; and a control circuit corresponding to each position of said signal each of which includes line wire extending to the rear of said signal, a front contact of the control relay corresponding to the same position and a back contact of each of the remaining control relays in series.

5. In combination, a stretch of railway, a wayside signal having at least three distinctive lamps for displaying at least three distinctive indications for governing traffic through the stretch, a slow release control relay for each lamp, a line circuit for each relay effective to energize its relay in response to a particular traflic condition in advance of the signal, and an operating circuit for each lamp each of which circuits includes a front contact of the associated control relay and a back contact of each of the other control relays whereand a clear lamp for governing traffic through the stretch, a slow release relay for each of the approach and clear lamps, a line circuit for each relay effective to energize its relay in response to a particular trafiic condition in advance of the signal, one operating circuit for the stop lamp including a back contact of each of said relays, and an operating circuit for each of the other lamps each of which circuits includes a front contact of the associated control relay and a back contact of the other control relay whereby flashing of the stop lamp at a change in trafiic conditions is avoided.

'7. In combination, a track block divided into a first and a second section which a train travels successively in moving through the block, a track circuit for each section each including a track relay, a signal having a clear and an approach position for governing trafiic through the block, a control relay for each position, an operating circuit for each position each of which includes a front contact of the associated control relay and a back contact of the other control relay, a line circuit for each control relay each of which includes a line wire and a front contact of each of the track relays, trafiic controlled means for at times energizing the line circuit for the control relay of the approach position and at other times energizing the line circuit for the control relay of the clear position, and means including back contacts of the track relay for the second section for short-circuiting the line Wires to the rear of said second section whereby energizing of a control relay by a cross on a line wire when the second section is occupied is avoided.

8. In combination, a stretch of railway track, a

signal to govern trafiic through the stretch and adapted to display a plurality of distinctive proceed indications'one for each ofa plurality of different trafiic conditions in advance, a plurality of control circuits each including a particular line wire and a common return wire, a current source having one terminal permanently connected to the common wire, a relay for each control circuit having its winding connected between the respective line wirecand the common wire, trafiic controlled means to connect the line wires to the other terminal of the current source in a particular arrangement for each of a plurality of different trafiic conditions for energizing the relays in a particular arrangement for each of said trafiic conditions, and a plurality of operating circuit means for said signal one for each indication and each such circuit means serially including a front contact of each relay energized under the trafiic condition corresponding to the adapted to display a plurality of distinctive proceed indications one for each of a plurality of different trafiic conditions in advance, a plurality of control circuits each including a particular line wire and a common return wire, a current source having one terminal permanently connected to the common wire, a relay for each control circuit having its winding connected between the respective line wire and the common wire, traffic controlled means to connect the other terminal of the current source to the line wires in a particular arrangement for each of a plurality of different trafiic conditions to energize at least a different one of the relays for each of saidtrafiic conditions, and a plurality of operating circuit means for said signal one for each indication and each of which circuit means includes a front contact of the relay energized under the traffic condition corresponding to the indication and a back contact of each deenergized relay.

10. In combination, a stretch of railway track, a signal to govern traffic through the stretch and adapted to display a plurality of distinctive proceed indications one for each of a plurality of different trafiic conditions in advance, a plurality of control circuits each including a particular line wire and a common return wire, a current source having one terminal permanently connected to the common wire, a relay for each control circuit having its winding connected between the respective line wire and the common Wire, trafiic controlled means to connect the other terminal of the current source to a different combination of the line wires for each of a plurality of different traffic conditions for energizing a different combination of the re.- lays for each of said traffic conditions, and a plurality of operating circuit means for said signal one for each indication and each such circuit means including a front contact of each relay energized under the traffic conditions corresponding to the indication and a back contact of each deenergized relay.

11. In combination, a stretch of railway track, a wayside signal to govern trafic through the stretch and adapted to display a plurality of different proceed indications, a plurality of control relays one for each of said indications, a control circuit for each of said relays and which circuit includes a particular line wire and an operating winding of the relay as well as a common return wire, a current source having one terminal connected to said common wire, means controlled by trafiic conditions in advance of said signal to connect the line wires to the other terminal of the current source in a particular arrangement for each of a plurality of different traffic conditions, and an operating circuit means for each of said indications and each of which circuit means includes a front contact of each relay energized under the traffic condition corresponding to the indication and a back contact of each deenergized relay.

12. In combination, a stretch of railway track, a signal to govern traflic through the stretch and adapted to display three different proceed indications, three control circuits each including a particular line wire and a common return wire, a current source having one terminal permanently connected to the common wire, a relay for each control circuit having its winding connected between the respective line wire and the common wire, means controlled by traffic conditions in advance of said signal to connect the line wires to the other terminal of the current source in a particular arrangement for each of three different trafiic conditions for energizing the relays in a particular arrangement for each of said traffic conditions, and three operating circuit means for said signal one for each indication and each such circuit means serially including a front contact of the relays energized under the traffic condition corresponding to the indication and a back contact of each of the remaining relays.

13. In combination, a stretch of railway track, a wayside signal to govern traffic through the stretch and adapted to display three different proceed indications; a first, a second and a third control relay; a first operating circuit for causing the signal to display a first one of said indications and serially including a front contact of the first relay and a back contact of the second and third relays, a second operating circuit for causing the signal to display a second one of said indications and serially including a front contact of the second relay and a back contact of the first and third relays, a third operating circuit for causing the signal to display a third one of said indications and serially including a front contact of the third relay and a back contact of the first and second relays; and means controlled by traffic conditions in advance of said signal operative to energize the first relay under one traffic condition, to energize the second relay under another traffic condition and to energize the third relay under a third trafiic condition.

14. In combination, a stretch of railway track, a Wayside signal to govern trafiic through the stretch and adapted to display three different proceed indications; a first, a second and a third control relay; a first operating circuit for causing the signal to display a first one of said indications and serially including a front contact of the first and second relays and a back contact of the third relay, a second operating circuit for causing the signal to display a second one of said indications and serially including a front contact of the first and third relays and a back contact of the second relay, a third operating circuit for causing the signal to display a third one of said indications and serially including a front contact of the second and third relays and a back contact of the first relay; and means controlled by traflic conditions in advance of said signal operative to energize the first and second relays under one traffic condition, to energize the first and third relays under another traffic condition and to energize the second and third relays under a third trafiic condition.

15. In combination, a stretch of railway, a wayside signal having a green and a yellow lamp as well as a red lamp for displaying two distinctive proceed indications as well as a stop indication, a control relay for each proceed indication of the signal and each responsive to traffic conditions in advance, a stop operating circuit including a back contact of each of said control relays and the red lamp, a first proceed operating circuit including a front contact of one of the control relays and a back contact of the other control relay as Well as the yellow lamp, a second proceed operating circuit including a front contact of said other control relay and a back contact of said one control relay as well as the green lamp, and said relays each characterized by being slow releasing whereby flashing of the red lamp in changing from one proceed indication to the other is avoided.

HOWARD A. THOMPSON. 

